Etching apparatus



1,643,234 sept 2Q, 1927. J. BAKER l y ET-CHING APPARATUS Filed Sept. 29, 1926 y2 Sheets-Sheet 1 Sept 2019277 J. BAKER 3 ETCHING APPARATUS Filedsept 29. 19,25 2 sheets-Sheet 2 Aon/y y g4 fg@ F7126,

Patented Sept. 20, 1927.

UNITED sTATEsi JOHN BAKER, or HANnswonTn, BIRMINGHAM, ENGLAND.

ETCHING APPARATUS.

Application aieiiseptember 29, 1926, serial No.

This invention relates to an improved method and means for treating zinc or other suitable printing plates by exposing them to the action of metallic acids subsequent to protecting the necessary parts from the action of the acid in order to obtain the requisite fine relief of the subject to be printed. Various methods of achieving this result have been in practice for a considerable time and the resultsfareP more or less successful. In some machinesfor mechanically obtaining` thisprocess of etching, the acid solution is agitated into a drifting spray, the plate to be etched being in the intense zone of the spray. Other spraying methods have been adopted, but unless a very expensive plant is employed the results are not always satisfactory. The object of this invention is to provide a means of etching metal plates by exposure to an acid, which does not require an expensive plant and which will be convenient and highly efficient in use. A further ob]l ect of this invention is to protect the operator from the acid fumes.

According to this invention the method 0f applying the acid to the plate to be etched consists in spraying a number of jets over the surface of the plate. The` jets cm1 be obtained by submerging into the acid a-perforated surface, preferably composed of a material not subject to corrosion by the acid solution.

Briefly the preferred embodiment of this invention may be said to consist in a receptacle for the acid solution, a plate having a large number of perforations therein, the said plate being disposed within the said receptacle and having means associated with it whereby the plate to be etched can be secured in spaced relationship above it, mechanism being provided for raising and lowering the perforated plate out of and into the acid solution at a speed suflicient to enr sure the acid solution being sprayed in jetform through the perforations over the surface of the plate to be etched.

The mechanism above referred t o may conveniently consist of a pair of horizontal bars 0 disposed above the receptacle and carrying by depending` vertical rods the perforated plate, the said rods passing through guides in the top or cover of the receptacle, and coiled springs being interposed between the bars and the top of the receptacle, the said 138,463, and in Great Britain October 10, 1925.

stracts the fumes from the receptacle and draws air into the receptacle. This pump maybe of any well known type, for instance bellows operated in unison with the mechanism for moving the perforated plate.

In order that this invention may bey clearly understood and readily carried into effect Ihave appended hereto two sheets of drawings, somewhat diagrammatically illustrating same and wherein Fig. l is a perspectivcview of the complete apparatus.

Fig. 2 is a perspective view showing the top of the acid receptacle and the aerating pump.

Fig. 3 is an enlarged detail view of` thev acid receptacle and associated parts showing .a modified construction, and

Figs. 4,5 and 6 show different methods of providing perforations in the perforated plate.

Referring to Figures l and 2 of the drawings, the plate to be etched is indicated by the reference numeral l, and itl will be seen that it is supported ina horizontal plane above and parallel to a perforated plate 2 which is adapted to be intermittently submerged `into the acidsolution contained in an acid-proof bath 3. The bath 3 is flanged around its upper edge as at t to support a three sided top late or cover 5 which accommodates afhmgedly supported frame 6 carrying a glass window 7 whereby the bath may be closed but its interior be visible to the operator. In Fig. 1 the frame 6 is shown open, and in Fig. 2 it is shown closed.

The perforated plate 2 has a surrounding shallow wall 2 so that itA has a tray like appearance', and it is suspended from four vertical rods 8 slidable through Vguides in the cover 5 and secured at vtheir upper ends to a pair of horizontal bars 9 between which and the top are disposed coiledspringsl() Which normally maintain the `perforated plate 2 raised above the level of the acid.

5 solution in the bat-h 3. y It will be apparent that if the perforated plate 3 is quickly submerged into ,the acidV 'drawings `andconsists'of an axially rotatable :shaft 11 supported inbearings 112 alongside the bath 3. One'end of this shaft isiprovided with a 'crank 13 forl manual operation, or may be" driven by :a `beltand pulley 'or other'kn'ownform ofdrive. The other end 'of theshaft llcarries a cam or if desired an eccentric 11i with the periphery of which engages a roller 15 carried by the 'free end ofanarni 16`pivotally supported at one end 17 and connected by a vertical link 18 to a rod`19 extending from the' centre of a yoke for 'U-shaped member 20 pivotally connected atits cranked ends 21 to uprights 22 carried by the top" 5. Y i i To enable the amount of submersion of thelperforated plate `2 to be predetermined the link 18 has a number` yof holes 182L to 'receiverthe pivot pin f23 of the arm 16, Whilst `the upriglits 22. if 'desired may beprovided with a number of holes 24 to receive the w cranked'ends 121'of the member 20.

The freeend of the rod 19 is` connected by a pivot pin'25 to the upper end'of a rod '26 pivotally connected at its lower end to a bellows lor other suitable eXhauster 27 which by means of a conduit 28 communicates with the interior ofthe bath 3, with a consequent automatic aeration of the bath 3 during the operation of the plant. 4The rod 19 can be adjustably connected'to the arm 26 by providing a number of holes26a to receive the pin 25.

The bath 3 and the other parts .of the plantare"carried by a suitablel frame 29 having 'a shelf-301m support the eXhauster 27. A coiled' springl connected at one end by a rod 32to vthe arm4 16,and at its'other end to an anchoring rod 33 maintains proper engagement of tlfevfree end of the arm `16 W ith thefcaml 14.

Inthe' modified construction shown in Fig. 13, th'ep'erforated plate2 is'provided at opposits" 'ends with doWnwa'rdly .extending Walls 12a and is Xed in the acid bathl in the position shown in such ama-nner as'toiform between the Walls 2L and the end Wallsof the bath 3 rectangular chambers which communicate with the space beneaththe plate date pistons or plungers 3l which are fixed tovert-'ical rods 8a slidingV in guides in the cover-"of the acid receptacle similarly to the rods 8 shown in Fig. 1. The rods 8a are actuated in the same Way .as the rods 8 of Figure 1 and the movement of the plungers 3 causes acid to be forced through the perforations in the plate 2 upon the surface of theplate to be etched, `which is carried on the-plate 2 by means of supports (not shown) similar `to those shown on the plate 2 in Fig. 1.`

My invention obviatesl many defects arisindI out of the useofexisting known forms of etching plant, inasmuch .asit ensures a rapid and regular application `ofl `theacid '1 to the'plate to be etched, Vit protects the operator fromthe noxious fumes from the acid, and the Waste in acid is reduced appreciably.

The perforations in the plate` 2 may take 'various forms and 4can be obtained in different manners, for instance inFig. 4, the plate 1-2`is shownwith conical or jetlike perforations 34;. In Fig. 5 `the perforations are obtained by superimposing a suitable number of-plates 35, in which holesu36 are provided so `arranged thatwhen the plates are correctly secured against each other the holes 3G are arranged in, sets on common axes, the holes in each set being stepped 1in diameter the smaller diameter being uppermost. In Fig.6 a still further modified jform of perforation is shown in the form of va downwardly/and outwardly flared hole 37 the upper end "beingveryrestricted Vin diameter. and if desired disposed ina boss 38.

The number, location and dimensions of 'the perforlations can be varied by having interchangeable plates 2. The jets may be` forced upwards `with greater power by increasing the effective thickness of the Vplate 2, by adding' to the base 'ofthe plate moulded `.coimterpart thereby increasing the` length of the-perforations and, according to the level ofthe acid,

`obtaining alonger compression action on the acid. For instance in Fig 5 the lower plate 4could be considered as an additional counterpart.

I clagimz-f 1. Apparatus for etching zinc `and other plates' comprising an acid receptacle, means for supportingthe plate to be etched above the level` of` the: acid in said receptacle, a perforated plate in lsaidreceptacle disposed `approximatelyi parallel tothe surface ofthe acid, reciprocating means in said receptacle for forcing the acid through said perforated jplate, to directa number of jets-upon the surface of the'plate to beetched, a' reciprocating exhauster for 4withdrawing fumes from said acid lchamber and an operative connection bet-Ween said reciprocating means and exhauster.

2. Apparatus for etching Zinc and other plates comprising an acid receptacle, means for supporting the plate to be etched above the level of the acid in the said receptacle, a perforated plate in said receptacle disposed approximately parallel to the surface of the acid reciprocating meansv in said receptacle having a lifting stroke for drawing acid through said perforated plate and a forcing stroke for forcing said acid through said perforated plate to directa number of jets upon the surface of the plate to be etched, spring means actingon said reciprocating means, to effect the forcing stroke thereof and a cam device acting on said reciprocating device aga-inst said spring means for repeatedly effecting the lifting stroke thereoperation.

3. Apparatus for etching zinc and other plates comprising an acid receptacle, means for supporting the plate to be etched above the'level of the vacid insaid receptacle, reciprocating means in said receptacle for directing jets of acid intermittently upon the surface of the plate to be etched, spring means for moving said reciprocating means in one direction and a rotary cam for re-` peatedly moving said reciprocating mea-ns in the opposite direction and then releasing the same.

JOHN BAKER.

l of and then releasing said spring means for 

